After the last “Hangover” film left most people with a sour taste in their mouth, it was no secret that director Todd Phillips would have to change up the formula if he ever made another sequel. Unfortunately, despite heeding that advice on the latest installment, “The Hangover Part III” is a really bad movie (like, worst film of the year bad) – a joyless and humorless cash-in that bears little resemblance to the 2009 original except by name. Say what you will about the first sequel, but at least that one actually felt like a “Hangover” movie. I’m still not even sure if “Part III” is supposed to be a comedy, but the shocking lack of laughter would suggest otherwise.

The film opens with a silly gag involving Alan (Zach Galifianakis) buying and subsequently killing a giraffe while transporting it home, and it only goes downhill from there. (Sadly, that’s also just the start of the movie’s streak of animal cruelty.) When his latest antics cause his father (Jeffrey Tambor) to have a heart attack and die, it puts Alan in a bit of tailspin. Concerned about his well-being, the guys (Bradley Cooper, Ed Helms and Justin Bartha) stage an intervention and convince him to get help at a mental health clinic in Arizona. On the way there, however, they’re kidnapped by a surly gangster named Marshall (John Goodman), who blames them for introducing Leslie Chow (Ken Jeong) into his life. Apparently, Chow stole a lot of money from Marshall and has evaded him ever since, so he tasks the Wolfpack (minus Doug of course, who’s kept as collateral) to track him down, taking them from Tijuana to Las Vegas, the city where it all began.

There are so many holes in the plot that you honestly wouldn’t know where to begin, and that’s just one of the countless problems plaguing the movie. “Part II” may have been a complete rehash in that it utilized the blackout drunk mystery scenario all over again, but at least there were some laughs to be had. “Part III” feels less like a comedy and more like a pitch black revenge thriller revolving around Galifianakis’ Alan, who for some reason has graduated from goofy man-child to borderline mentally challenged. And if “Tropic Thunder” taught us anything, it’s that you never go full retard. Even worse than Galifianakis’ annoying shtick is Ken Jeong’s over-the-top gangster. Jeong is one of those comedic actors who’s tolerable in small doses, but his role in the “Hangover” movies has grown with every installment, and it’s no coincidence that his involvement is directly related to the decreased quality of each film.

The rest of the guys are on auto-pilot, simply going through the motions to collect their paychecks, although Cooper is still enjoyable as the straight man of the trio. And can you really blame them? The script is so terrible and devoid of laughs (despite some half-assed attempts at humor that rarely land) that it’s hard to imagine anyone signing on to the movie for anything other than the great payday. The film mostly runs on nostalgia – a fact made clear by the return of several familiar faces, even if they have nothing to offer the story – but even that little bit of fan service sputters out well before the end, much like the finale itself. Instead of making up for the last movie, “The Hangover Part III” only further spoils the legacy of the first film, leaving audiences feeling even more violated than before.